[3] Although Watanabe was known as a 125cc class rider, he scored a surprising first moto victory over 500cc world champion Roger De Coster at the 1976 Trans-AMA race held at the Mid-Ohio circuit.

Watanabe won three Grand Prix races and consistently scored points while his rivals suffered accidents or mechanical problems to become the first and only Japanese competitor to win an FIM motocross world championship.

[1] Watanabe returned to Japan where he continued to work in the Suzuki racing department as a development and test rider until 1988.

[1] He competed in the 1991 Paris to Dakar rally at the suggestion of his former Suzuki teammate Gaston Rahier.

[1] Watanabe opened a motorcycle shop in his hometown and became an organizer of enduro off-road races.